A well plan describes the well trajectory to be followed to to take a well successfully from its surface position to the end of the well trajectory. Based on factors such as an expected use of a well (e.g., observation, production, injection, or multi-purpose well), parameters (e.g., production parameters, completion requirements, well dimensions, location), an expected life of the well, and conditions of the geological target (e.g., the subterranean reservoir) to be reached by the well, and other factors, the well plan outlines well objectives to be achieved during well drilling and well use. When drilling commences based on the well plan, the well can be periodically surveyed to obtain information describing the well being drilled and the obtained information interpreted, e.g., to compare a planned position and a determined position of the well. An operator can respond to deviations between the planned position and the determined position, e.g., by adjusting the drilling operations or by re-defining the well objectives (or both).
Like reference symbols in the various drawings indicate like elements.